#include <stdio.h>

void deblank(char a[]) {
    for (int i = 0, j = 0; a[i] != '\0'; ) {
        int flag = 0;
        while (a[i] != '\0' && a[i] == ' ') flag = 1, i++;
        if (flag)
            a[j++] = ' ';
        a[j++] = a[i++];
    }
}

int main() {
    char a[50] = "Hellow   world!";
    puts(a);
    deblank(a);
    puts(a);
}